Reproductive neurogenetics in Drosophila involves a widening array of behavioral and neural mutants as well as molecular manipulations involving factors that influence sex-specific features of the fly's nervous system. To extend the analysis of semi-classical courtship genes, the roles played by calcium-channel polypeptides and nucleic-acid binding proteins will be dissected. For the former of these two genes, cacophony, the experiments include molecular- genetic analysis of courtship-song defects and visual-system ones as well (the latter being caused by certain of the cac-locus mutations). The significance of posttranscriptional variation in channel quality will be assessed, including molecular manipulations and behavioral bioassays of putative RNA editing events involving cac s primary product. The no-on-transient-A gene also can be mutated to cause singing and visual abnormalities. The significance of nonA's spatial expression will be dissected, principally in terms of a novel abnormality of courtship-humming sounds associated with transgene manipulations of the normal allele. How nonA and the putative RNA-binding protein it encodes may interact with cac will be determined, in part by determining whether in vivo an and engineered nonA mutations affect post-transcriptional processing of the Ca2+-channel RNA cac's behavioral and molecular-genetics suggests one way that courtship songs diverge evolutionarily: by modulations of patterned neuronal outputs caused by calcium- channel variations; this will be investigated by analyzing inter- specific relatives of cac and bioassays of the molecular variants in transgenic males. The genetics of sex determination will be further merged with courtship studies by behavioral and pheromonal analysis of fruitless and doublesex mutants; the experiments include molecular neurogenetic dissection of courtship-hum abnormalities and analysis of sex-specific locomotor behavior. To move in certain new directions, the genetics of female receptivity will be analyzed by neurobiological and molecular studies of a new mutant; also, possible resets of a biological clock, induced by conditioned courtship stimuli, will be investigated to see if parallels can be drawn to a novel finding in this area from mammals. -- Reproduction seems on the face of it to have broad significance. Variations of these phenomena, caused genetically in organisms ranging up to humans, are being increasingly appreciated, analyzed, and manufactured experimentally. It is suggested that neurogenetic and molecular neurobiological findings and principles, stemming in part from studies of Drosophila courtship and mating, may contribute to the design and interpretation of investigations in this area, which would involve a variety of different organisms.